containers/podman

Support local volumes with a lifetime longer than that of the podman host

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#18,075 opened on Apr 5, 2023

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Good First Issue

Description

Feature request description

Having the ability to retain volumes on a mounted filesystem is desirable as it allows for the replacement of the host system without losing the content of persistent volumes.

This is particularly useful when podman is used on a virtual machine with attached storage, where system upgrades involve replacing the virtual machine. While bind mounts or hostPath volumes could be used, managed volumes are more convenient, especially when podman-kube is already used to manage all other supported resources. Managed volumes offer the advantage of automated cleanup of volumes.

Suggest potential solution

As far as I can tell, the current behavior, although not guaranteed or documented, works as is with volume_path set to a directory on a mounted filesystem. Since podman does not modify the volume directory during volume creation, podman can be made aware of pre-existing volumes, simply by (re)creating volumes with the same name. However, to make it a reliable and supported feature, there may be additional changes required.

Have you considered any alternatives?

No response

Additional context

The behaviour was also mentioned in #16245, but with the opposite intention of using transient volumes.

Contributor guide

Tech stack
go
Domain
backendinfrastructure
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Go programmingPodman volume internalsLinux filesystem mountsContainer storage basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate how Podman currently creates and manages volumes, particularly the volume path and lifecycle. Review the discussion in #16245 for context on transient volumes. Explore the volume creation code in libpod/volume.go and related tests to understand how to extend volume persistence beyond host lifetime. Consider implementing a new volume option or modifying the existing one to ensure volumes survive host replacement.